This scenic route follows central Idaho’s largest river north from its headwaters in the Sawtooth Range through desert canyons to the tiny town of North Fork, where the waters swerve suddenly to the west and leave all roads far behind. The drive then heads back into the mountains, following the path of Lewis and Clark over Lost Trail Pass and down into the Bitterroot Valley. It’s a gorgeous drive and one that touches on the themes of exploration, fur trapping, mining, settlement, and Native American heritage.

The route begins in Stanley, on the floor of Stanley Basin and in view of Idaho’s most spectacular peaks, the Sawtooth Range. Follow Idaho 75 east to the Stanley Museum, which summarizes the area’s mining and ranching past in a small, historic ranger station.

Paralleling the Salmon River, the road soon slants down into a forested gorge lined with granite outcroppings. The river—clean, cold, and swift—drops 15 feet a mile, charging through turbulent rapids and sweeping past several hot spring pools. Sunbeam Hot Springs, the best known and most obvious of the springs, trickles down a rocky slope about 11 miles from Stanley. Less than a mile beyond the springs, the river stalls out in deep pools of emerald green and turquoise at the crossroads town of Sunbeam. The dynamited remains of the only dam ever built on the Salmon River stand below an overlook.

Follow the river 2.5 miles east of Sunbeam to Indian Riffles, which overlooks spawning beds for chinook salmon. Years ago, chinook and sockeye salmon migrated through here in such numbers that locals said you could almost walk across the river on the backs of spawning fish. No longer. Hydroelectric dams on the Columbia and Snake Rivers have endangered both species.

The road continues along the Salmon River through small canyons that get wider and drier as you descend. Beyond Clayton, the river bends to the northeast and runs through a valley surrounded by high desert hills. This eroded volcanic landscape was carved from ash and lava that spread across the region 50 million years ago from calderas lying northwest of Challis.

Approaching the junction with US 93, you pass under a towering cliff of rust-colored rock. Bighorn sheep frequent the area, and so did bison in earlier times. At the Bison Jump Archaeological Site, a sign describes how Native Americans drove small herds of the animals over the cliff.

As you head north from Challis, founded in 1878 to supply the mining camps, look for pronghorn on the desert floor and hawks wheeling overhead. To the southeast rise the gravelly, colorful ramparts of the Lost River Range.

Soon you cross the Pahsimeroi River and then round the northern flank of the Lemhi Range. About 18 miles past Challis, both road and river punch through a narrow gorge that widens into a spectacular canyon. The walls soar hundreds of feet above the river to cliffs that cut a gap-toothed silhouette across the sky. Just south of Salmon, you begin to cross the Lemhi Valley. On the far side are the Beaverhead Mountains, a massive block of Precambrian sedimentary rock that slid east during the general uplift of the Rockies some 70 million years ago.

Follow US 93 to Salmon, an 1860s mining town and now a center for ranchers, loggers, and river runners. Here, you can pick up the Lewis and Clark Drive, tracing the explorers’ route over Lemhi Pass.

Heading north, the road runs through yet another canyon carved by the Salmon. Look for great blue herons, cliff swallows, deer, pronghorn, and maybe even river otters.

At North Fork the river plunges west into the Salmon River Canyon, one of the continent’s deepest gorges. Rushing across the vast wilderness of central Idaho, the river is no less forbidding today than it was when early explorers named it the River of No Return.

US 93 tunnels through dense forests to Lost Trail Pass, 7,014 feet, named in 1805 by the bewildered northbound party of Lewis and Clark. In 1877, during their epic flight for freedom, the Nez Perce also crossed east through these mountains into the Big Hole Valley. At the Big Hole National Battlefield, you can walk over the ground where the Nez Perce beat back the army.

From the pass, you descend into the Bitterroot Valley, a region heavily dependent on logging. Stop at the Indian Trees Campground to admire stands of mature ponderosa pines, whose reddish, plate-like bark can smell like vanilla.

South of Darby, the high peaks you’ll see to the left are the Bitterroots; the low-lying mountains to the right are the Sapphires, which once overlay the Bitterroots. As the Bitterroots rose, the Sapphire Mountains slid 50 miles to their present location.

On the Way: If you've a mind to soothe your sore muscles with a soak in the riverside Sunbeam Hot Springs, best plan on arriving early to beat the crowds.

Before You Come: Read A River Runs Through It and, as anglers fervently flick their lines into the current, the truth behind the book's famous first sentence—"In our family, there was no clear line between religion and fly fishing"—suddenly becomes clear.

Side Drive: Get a peek into the 3,600-square-mile Frank Church River of No Return Wilderness by following Salmon River Road as the waterway abruptly turns west at the village of North Fork.

Be Safe: While a dip in the river may sound refreshing on a hot day, remember it is fed by snowmelt and can quickly cause hypothermia even in summer.